Astronomy is study of celestial objects (such as stars, galaxies, planets, moons, asteroids, comets and nebulae); the physics, chemistry, and evolution of such objects; and phenomena that originate outside the atmosphere of Earth, including supernovae explosions, gamma ray bursts, and cosmic microwave background radiation.
Astronomy is one of the oldest sciences. The early civilizations in recorded history, such as the Babylonians, Greeks, Indians, Egyptians, Nubians, Iranians, Chinese, and Maya performed methodical observations of the night sky. However, the invention of the telescope was required before astronomy was able to develop into a modern science.
Astronomy is one of the few sciences where amateurs can play an active role, especially in the discovery and observation of one off events and amateur astronomers have made many important astronomical discoveries.